Photographic resist or film



Patented Nov. 24, 1931 v UNITED STATES PATEN r OFFICE JOHN was, or wnsrmnn, mm m assmnon r s'rn. confirm, or m w your. at. Y. a conrom'rron or mrw YORK DEMOGRAPHIC RESIST OB FILE Io Drawing. Application fled A ril is, 1927. Serial 1%. mam.

This invention relates to'improvements in either destroys or weakens the sensitivenesl photographic resists or films and more arof the resist to the action of light. tioularly to that class of light sensitive lms The chromate eosin solution is then mixed used in photo-engraving which are-adapted with the shellac-dragons blood solution above 5 to be flowed on to metal plates, where said mentioned and carefully filtered. After filplates are etched directly for printing purtering, it is boiled and kept in a cool dark poses after the development of said films. place.

I have devised a new resist or li ht sensi- I have found this composition especially. tive film which can be equally welI used on adapted as a resist or (photographic lm for 1 copper, zinc, brassor aluminum lates. The the etching of zinc an other metallic lates go resist is stable and plates of uni orm quality such as copper. Such a film canbe deve oped for printin purposes can be rapidly made with the ordmary developers heretofore used b th use time for the development of shellac-chromium My improved composition of matter is films and as they are well known to the photomade as follows: 12 ounces of bleached white engraving art, I do not give any formulas as shellac, 17% ounces of orange shellac, and for such developers herein. While I refer 7% ounces of borax are mixed together and to use ammonium chromate, it is wellown to these three ingredients are added 24 ounces t other oxidizing c mp n s h ve a i of a dragons blood solution. This dragong ilar action upon shellac, and these other so blood'solution is made by dissolving 16 ounces oxidizing compounds are to be considered as 70 of dragons blood in 69 fluid oun es of equivalents for the purposes of my invention. methyl-alcohol CI-LOH. The four ingre- The advantage of using the borax is that dients, bleached white shellac,o'range shellac, 1t permits the formation of an a ueous soluborax and dra ons blood solution are now tion of the shellac and dragonsb ood. This 25 added to 200 uid ounces of water and the filVCS a clearer solution than if ammonium 18 entire mixture is boiled for twenty minutesydroxide was used. The solution made ac in which time all of the solid ingredients go cording to my invention is substantially free into solution. This mixture is then cooled. from slime, 'it is easier to filter and the I then separately prepare the following operator is not annoyed by the fumes of amso solution. I monia when the metal plate is being coated. a.

I dissolve 3.1 ounces of ammonium chro- Likewise, the borax solutioncan be used on mate (NIL) CrO in 40 fluid ounces of water. copper plates because borax does not attack 7 o the solution of ammonium chromate I add copper. Likewise, it willbe noted that I use.

one ounce of an aniline tinctorial dye'and for ammonium chromate instead of ammonium V a; this 'pm'pose I prefers solution of eosin. A bichromate. Ammonium bichromate is not ll. dye which I'prefer to usefor thispurpose effective for the purposes of my invention, bef is made by dissolving 10 grains of eosin A cause when this salt is added to a borax soluwhich is an alkaline salt of tetrabromo-fluotion of shellac, aprecipitation of the dissolved resceine in, 16 fluid ounces of water and of shellac is produced. This is because am;

so this eosin solution I employ one ounce with monium bichromate is too. acid in-reaction, so. the aforesaid solution of 3.1 ounces of amand I therefore utilize a substantially neumonium chromate; Heretofore it has been. tral chromate'. customary to dissolve the shellac or the like Having fully described my invention, what in a solution of ammonia water (NI-LOH) I claim is:

4.5 in order to prepare the resist. This was ob- -1. A composition of matter for a light sen- 0 6,

' jectionable because the use of ammonia solusitive photographic film comprising shellac, tion was disagreeable. In addition I have borax,-dragons blood, ammonium chromate discovered that if the resist is used with a and eosin. I copper plate, that the presence of the am- 2. Acompo'sition of matter'fqr a light sen- I I0 monia causes copper to enter the resist, which sitive photographic film comprising shellac, 1g!

borax, dragons blood, ammonium chromate and an aniline d e.

3. A composition of matter for a light sensitive photographic film comprising shellac,

5 a non-volatile solvent for said shellac, dragons blood, ammonium chromate and eosin.

4. A composition of matter for a light sensitive photographic film comprising a mix-, ture of white and orange shellac, borax, am-

0 monium chromate and eosin A.

5. A process of preparing a light sensitive hotographic film by dissolving shellac and orax, adding thereto a solution of dragons blood and mixing said solution with a solu- 16 tion of ammonium chromate and eosin.

6. A method of securing a solution of a light sensitive'resist fora metal plate which consists in dissolving dragons blood and shel- I lac in a solvent which is unaffected by cop- 20 per, and then adding thereto a solution of ammonium chromate in a solvent which is also unaifected by copper.

7. A solution of a light-sensitive resist intended and adapted to be applied to'a metal plate, said solution including shellac and ammonium chromate, said solution being substantially free from material adapted to attiickdthe plate to which the resist is to be ap- P 8. A solution of a light-sensitive resist intended and adapted to be applied to a metal plate, said solution including shellac and ammonium chromate, and being substantially free from ammonia.

9. A solution of a light-sensitive resist in tended and adapted to be applied to a metal plate, said solution consisting substantially of water containing dissolved borax and dissolved shellac and dissolved ammonium chroao mate, and solution being substantially free from material adapted to attack the plate to which the resist is to be applied.

In testimony whereof I afiix my signature.

' JOHN HELFRICH. 

